Air to breathe and CO2 scrubbing equipment (electrolysis does not turn CO2 into carbon and O2, it turns water into O2 and H2), food (no fishing in space), waste water purification and recycling equipment (not done even on ISS), radio communication (unless he will do all his own navigation without help from Earth), attitude thrusters, radiation shielding, space suit (unless he stays in the vehicle all the time on Mars) all weigh how much? Does this person want to land on Mars? How much will the heat shield and parachute weigh? The thin atmosphere requires a very big parachute plus retro rockets just before landing. Does he want to come back? What mass fraction will the return vehicle have? Then toilet paper and tooth brush put you over 100 kg, don't you think?

The food problem is solved since the discovery expeditions done by people like Franklin und others. They had dry meat and dry bread onboard their ships and water supply too. Some problems to keep that food fresh and eatable are solved since that time.

The large volume of their ships were necessary to have room for the large number of crew members - that large crew will not be onboard a vehicle towards Mars at the first trip to that planet. This now in turn reduces the volume required to store food significantly.

Another portion of the volume of the discoverer's ships has been provided to be able to carry things from discovered territories back home. That large volume won't be required at a manned Mars mission too.

So a vehicle for a Mars mission can be much much smaller than the smallest ship of the discoverers without causing problems in storing enough food.

Good questions. There are people out there who can create real (not NASA style) answers. That’s what my “Help Wanted” thread is about.

Note that I mentioned one way? There are people willing to go (not me).

Yet this morning I remembered that reaction mass for a rocket can include inert material (like the air flowing through a propeller). Pump CO2 into a container to get liquid, and heat it later to use it (but the benefit is severely limited). ( Plus I seem to recall seeing Magnesium burning in pure CO2? It might take less to get back up than I expected.

Also note that with a better final stage the numbers are modestly better (as I expected in my first estimates), although still ridiculously small. Possibly 150 kg to Mars.

Communication and navigation are surprisingly easy, will detail later.

As noted, the “Water Gas reaction” (CO2 + H2 <> CO + H2O), recaptures half the oxygen from this component of metabolism – converting it to additional water. The rest is already in water. These together exactly balance the Oxygen use in carbohydrate or lipid metabolism (with the lost Oxygen equaling that contained in the food itself). Other options are possible including reducing CO (I need help here, you chemists!)

“(not done even on ISS)” No one flew around the planet on one tank of gas before Rutan.

The human system (standard size) is a heat engine running at an average of 100 Watts power. An efficient fuel cell (run backward) will supply the Oxygen need with 110 watts of electrical power.

Color film was prototyped in a bathtub. You could prototype an Oxygen reprocessor in yours, and then downsize it to flight weight.

A can of “Dust Off” is a controllable attitude thruster. A slow spin, and well selected moment of inertia matrix, will eliminate wasteful mini adjustments.

Come on guys! Make it light and make it work! Hugo Vihlen (the mini boater) had to do some hard thinking – so will the first person to Mars!

Radiation shielding: In case of a Solar Flare, get behind your stack of food and pray that its enough. Without the Flare – stop reading science fiction disguised as the real thing. The low energy cosmic radiation is much higher in an airliner than either on the ground or in space. The really high energy radiation is not blocked by the Earth’s magnetic field, and thus has been experienced by all astronauts in space. Radiation sickness or an early cancer death has not been characteristic for astronauts.

“But the risk on a trip to Mars is greater!” The risk is a lot greater, and radiation has little to do with it. Future health hazards stops few athletes, and won’t stop those who really want to walk on Mars either.

Descent to Mars, (60 kg descent mass), 2 kg for “Densified PICA” (NASA 1997) for heat shield, I calculate 3 kg for 12 meter diam, 25 micron thick polyethylene or Mylar, to slow descent to 30 meters/sec. Then 1.5 kg for two Cesaroni PRO38 765J330-16A motors to arrest descent. (I will detail this as “Prairie Lander”™ system in a separate thread). I have had excellent results with this motor.

I believe the F-22 “Partial Pressure Suit” was chamber tested to 66,000 ft altitude (about .75 psi air pressure). This is pretty close to vacuum (and even closer to Mars). It is essentially a “counter pressure suit” (using the “G” suit components for chest banding). This approach could make the “spacesuit” almost nylon coveralls and a facemask! (Extra small, as planned). (I again ask for help from people who really know about this stuff and for someone to provide a place to test new versions. The later facility can easily be built in a garage).

Food: 125 grams a day of “Super Atkins” (all fat) diet yields 1125 Calories a day. This could sustain life for my mini astronaut. 32.5 kg for 260 days. (Someone get me real numbers for near starvation diet).

Water recycling: (will detail on “Science Fair Projects” thread), reverse osmosis for stage one, with a small centrifugal evaporator for stage two. About 20 grams per day (for standard sized human) of soluble salts collects in (replaceable) reentrant plastic spinner.

I am only half serious about this 670 kg plan. But really thinking about it will let you realize that the Falcon 5 (or a number of already operational vehicles) is more than big enough to take a mini mission round trip to Mars.

Don’t get in the habit of throwing in an extra ton whenever the problem is challenging – do that sixty times and you have a Space Shuttle!

Most people don’t get beyond laughing about a 6 foot sailboat to cross the Atlantic. A very few think harder, and trim it down to 5 feet 4 inches!

You could prototype an Oxygen reprocessor in yours, and then downsize it to flight weight.

Yes, that is the trick, isn't it?

But 60 kg empty weight for a manned vehicle to Mars is just ludicrous. I would think the absolute lowest weight for a craft to make one orbit around Earth would be that, or even higher. 32.5 kg food for 260 days, is that the round trip time you are planning? It sounds like the one way time to me. So he starves right after landing. But since he has no way to take off again, that is no problem. Don't get me wrong. I am all for smaller simpler vehicles, but 60 kg, or even 150 kg for man to Mars? Get real! (EDIT) A Mercury capsule was over 1,000 kg for crying out loud.

I agree with you. This was an exercise. Someone like Hugo Vihlen might take it seriously.

What I am serious about is a 100 kg space suited individual orbiting in a 100 kg open frame capsule. (The aerodynamic shroud is ejected early, as usual, to reduce its impact on orbital capacity). Fail safe "counter pressure suits" are feasible.

I don’t consider the Mercury any more “optimized” for orbital flight than I consider the F-16 a good one man sport plane.

Yet the numbers, with moderate adjustment (less than an order of magnitude) are also real for human flight to Mars.

I like to think of SpaceShip One as the Aeronca of the space age. Simple, cheap and low capability. The space shuttle is more like a Boeing Stearman. What you are talking about is more like an ultralight. Ultralights are great fun to fly, but you don't go crossing the Atlantic in one. Your ultralight space craft may be good for suborbital and LEO fun flights, but don't try to go to Mars in one.

I plan to stick to the 125 gm/day diet. I remember reading about an extreme backpacker who lived mostly on butter. I am counting on my “Science Fair Kids” to prove that you don’t need a “Manhattan Project” to grow slime mold. Their product will enhance the diet (and the CO2 recycling). (My best reference is “Algae as Food”, Scientific American, Oct. 1953, Volume 189, N0.4 (yeah, I remember reading it when it was published!) Google didn’t find anything better for me.)

Now for the tricky part, off the planet: Mars.

I won’t propose waiting for Zubrin in this estimate, because I don’t think he is ready. That Falcon 1 robotic probe could get a working prototype of his onto Mars if he were thinking in that direction, but that’s another story. A Mars exploration, not just footprints, will need his contribution to increase return mass capacity.

But my lucky little astronaut will go upstairs, all suited up, at 50 kg. LMO (Low Mars Orbit) takes 362 g*sec (to give 3550 km/sec). Minuscule air drag and low gravity loss: add 10% for orbital insertion. I like Hydrogen Peroxide fuel systems (also serves as a good source of emergency Oxygen, water and heat. I am fascinated by its potential for high altitude mountaineering.) Since this project needs efficiency, use with Hydrazine, which although nasty, increases the combustion energy and is a good peroxide catalyst. Both peroxide and Hydrazine are usable monopropellants, but combined they exceed 300 seconds vacuum ISP.

This gives a 3.77 mass ratio to orbit. Rounding up to 4.0 (so I can pretend that I am occasionally conservative in my estimates), we need 180 kg of fuel to get 50 kg of astronaut plus10 kg of rocket remains into LMO. Yes, 10 kg is sufficient for the rocket motor, fuel tanks, plumbing and control system. HEY, this is the stuff I am ACTUALLY BUILDING!

Then the rendezvous. With good launch control, and no hurry, this uses negligible fuel. A polar orbit and landing on Mars would radically simplify this. I will discuss communications, telemetry, tracking and control separately. For the moment let me mention that an adequate PIC microcontroller can hide in an aspirin tablet!

The stay at Mars is a problem. The time on Mars itself can be kept short for safety, and with little equipment, studies won’t be very sophisticated. This is outlined as a “Footprints and Feasibility Demonstration”. With the budget ratcheted up an order of magnitude (still a small fraction of present plans) serious study can be done. But minimum energy transfer requires a delay at Mars over 1.5 Earth years before return. A lot of food gets burned while watching Gilligan’s Island DVDs. Leave it that way until I can compute other orbits – they may be equally feasible.

By the way I was kidding about a minute hovel. A one meter diameter pressure hull, two meters long, using my present construction, would mass under 10kg. Boosting this to an echoing two meters in diameter and three meters long (a big bizjet cabin), is under 30 kg. Add Styrofoam furniture, and enjoy

Boost back toward Earth takes only an additional 210 g*sec( 2060 meters/sec). Sticking with my 300 sec ISP fuel, this takes a mass ratio of 2.02 Thus fuel needed at this point is 101% of the returned mass with rocket remains. Using my current rockets structural efficiency, the last term is 5% of Earth return payload. That boosted mass must now include the 65 kg of food for two compact astronauts during the 260 day return. To be continued …

This is a bottom up effort, and I am still filling in the pieces. If you can offer expert information on defects of my assumptions, I want to hear them. Yet even I never expected to be using microcomputers (and MEMS gyros) I could safely swallow! So opinions, in science and engineering, are made to be proven wrong.

Yes this is an ultralight, like polar and mountaineering firsts (Amundson was outstanding at lightweight efforts). Not everyone yearns to be the one hundredth person to step on Mars. Nor do following “adventure” efforts (like the tenth Everest summit team) get much publicity or sponsor funding. I can’t quite see how a following, more comfortable (and expensive), effort will ever be funded! I can’t see congress coughing up a gigabuck to send the tenth expedition to Mars!

Last edited by rpspeck on Mon Mar 14, 2005 12:45 am, edited 2 times in total.

If your proposed vehicle could get a person to Mars orbit, then it could take that same person on a suborbital X-prize type flight right here on Earth. So if you succeed in doing that I'll have to believe you. 10 kg empty mass for a working one man suborbital vehicle is really hard to believe.

Reality is often surprising. I was amazed the first time I read about powered hang gliders which one could carry strapped to the back. After launching into the wind, the user could cruise in the air for an hour!

I was surprised to realize (and demonstrate by power scaling) that a one Watt radio signal (on 2 meter band), with trivial antennas, could produce an audible (cw mode) signal from the Moon! This in spite of the fact that my “5 Watt” CB handhelds got nothing 2 blocks down a city street.

The “audible” signal was sufficient to send text faster than anyone can type, plus 10 minutes a day of internet video or a mix with high resolution snapshots. Using a moderate antenna on the spacecraft and a serious antenna on Earth, this range jumps to 50 million miles. (A “serious” antenna, for a radio Ham, would be an array costing as much as a new car). Upping power to a still paltry 10 watts would sustain this communication throughout the Mars mission, with some data rate reduction through conjunction.

I was surprised to read that resonant compact antennas could have high efficiency. I proved this fact by shrinking the critical dimension of my “2 meter” telemetry transmitter antenna from a traditional 40 inches to 1.2 inch, but still getting 50% efficiency!

And I was amazed ten years ago to discover that modern composites offered such a high strength to weight ratio (an order of magnitude above metals), that simple pressure fed rocket motors should approach or exceed the launch performance of the big, turbopumped systems! We achieved this from the engineering standpoint in Y 2000 with production fuel tanks. We are closing in on it with our ongoing flight tests.

Regarding your specific observations: The 10 kg of “rocket remains” is 20% of the payload mass. At 4:1 mass ratio this is only moderate for modern rockets. Use on Earth adds a penalty for higher gravity (thus higher thrust to keep gravity loss down) and higher operating pressure to keep the pressure ratio high in the first stage. We are closing in on 40% for this mass ratio in low altitude (Earth) use. Upper stages should reach the 20% value.

I have assigned my astronaut an unwelcome 25% of body mass for gear. This is on the high end for extreme skydivers. When Malcolm Ross and Victor Prather ascended to 113,500 feet (1961) in an open frame “seat”, their load was probably no higher. At this altitude air pressure is closer to space than that of the Martian surface. What they did in 1961, we should be able to accomplish in related environments now.

I am presently using lower energy fuels than those listed for Mars. The air drag in Earth’s lower atmosphere is serious and impacts the performance. Still, I expect to loft an astronaut into space with a system having an empty weight less than his body weight.

Endless arguments can be made about what will constitute a “really credible” demonstration and what is the necessary environment. Some insist on heavy walls, as if 125,000 pounds of structure could protect the Columbia astronauts from the real hazards! I know that it is always possible to multiply complexity, weight and cost. I choose to make do with coach, and skip the 4X cost factor of flying First Class.

Returning to the scenario: For life support, the “CoolFC-10” (fuelcellstore.com) unit, run backward, is excessive for my needs, at 2.5kg mass. It should electrolyze more than twice the requires H2O to O2. The first stage reverse osmosis system (for wash water) could use the 98 gram , “ASF Thomas”, mini peristaltic pump I have used for a fuel pump. It is excessive, pumping 43 liters of water a day. But mass is tolerable, and it runs on 1 to 2 Watts. The evaporator system would use a spinning plastic shell the size and shape of a raised doughnut. At 10 revolutions per second, it would stabilize the liquid with ½ g “centrifugal force”. Radiant heat would evaporate the one drop every ten seconds that it needs to handle (400 cc/day of concentrate). Power input would be about 10 Watts. Evaporation to dryness would stabilize the contents for planned acceleration. Estimated system mass is 500 grams. A matching feed pump is a challenge. The LPLA (TheLeeCo.com) is interesting, although it has a capacity 20 times that required, and at 50 grams is a modest weight saving. A common, replaceable pump is probably the best for the units in this system. Total recycling system, estimate 5 kg.

It looks like you (campbelp2002) are the only one reading this. I get trapped with a compulsive fixation on working through details like this, but I don’t need to inflict it on anyone else. So to jump to the bottom line:

This totals 915 kg boosted from Earth on Mars transfer orbit.
Mass ratio 4.0 handles boost from LEO with the assumed ISP and dead weight. Giving 3660 kg in LEO. Since this is less than 2/3 the estimated capability of the Falcon 5, this should be a doable flight. I probably missed some pieces, but I know that several numbers are too high.

To repeat, 3660 kg in low Earth orbit will allow two lightweight astronauts to travel to Mars and back: one will descend to Mars’ surface before rejoining for the return flight.

I get compulsive about working out the numbers too (see orbital mechanics in technology and lunar tourism in cafe), so we are birds of a feather.

You speak of breaking water into oxygen and hydrogen, but our astronaut does not need to do that. He needs to break CO2 into carbon and oxygen. No light weight way to do this has been developed yet as far as I know. In the ISS and on nuclear submarines there are CO2 removers, but they just remove the CO2, they don't recover the oxygen.

And I still doubt that such a light (10 kg) rocket could be made large enough to hold a person. Certainly Armadillo has come nowhere near that light.

I am reading your posts too - and they are very interesting and delighting. Concerning the CO2 I today read of a technology to get the CO2 out of the earthian atmosphere - this technology might be of use within a space vehicle too. I will have a new look into the article and post it in the board - Technology section perhaps - and provide a link to that post here.

Someone thinking far outside the box could be the first to walk on Mars! I am serious that a midget in a micro craft (probably more than 6 feet long) would have a shot at it. I concede that the Falcon 5 makes far more sense (with a one year delay?). I don't concede that a mega billion dollar NASA effort is worth waiting for (and I don't think one will ever happen).

You're not only thinking outside the box, I think your thoughts have left the building.

From my restricted perspective your minimalist approach stretches but does not break the limits of plausibility for a sub-orbital hop ... but to mars?

You want someone to lie down in a coffin for the best part of a year? You're going to need some sort of (as yet undeveloped) suspended animation trick for that or you're going to end up with a starved-to-death skeleton at the other end. If humans didn't need food, air, regular excercise, some room to move in and shielding then ... ok ... maybe.

Just a thought rpspeck, would a couple of kg extra weight for an inflateable section be worth the trouble? If your two wee friends are to stay away for such an extended period, then a little more room might help. Also, two blokes would get on okay I guess, but a couple would get on better. At least when things are slack or stressful, they could have a hug, and that might go a long way to ensuring success.

Here's another wee thought. Could your ship be docked and stocked from the ISS prior to leaving Earth for Mars? Everything you are doing is trying to save weight so the launch system can cope, but if you could send it up half empty (yet still at the max for the lauch system), then stock up for a day or two with the ISS, and boost on to Mars... dunno! Just a thought.

Before I start getting snippy about this ... surely you don't mean an inflateable section is going to weigh only 2 kg? Given that the Genesis Pathfinder (Bigelow) is 1250 kg ... according to this site ...